How can I make different particles follow many curves in same scene?
For slower particle speed change the lifetime value of the particle system to a larger value.
For faster particle speed change the lifetime value of the particle system to a smaller value.
The setting is in the particles settings emissions panel
So the length of a curve and the lifetime combine to create speed
The arrow in the Blender screen capture below shows the setting with an arrow




A previous answer regarding multiple Curve Guides ..

How to isolate emitted particles to a specific Curve Guide?



I am addressing two different topics since I cannot tell how many different concept questions are in the Blender question above.